1. Field of the Invention
The present invention relates to an image forming apparatus of, for example, electrophotographic type such as a copying machine or a laser printer, and more particularly, it relates to an image forming apparatus capable of forming a color image on a recording material, and a cartridge detachably attachable to such an image forming apparatus.
2. Related Background Art
For example, as one of color image forming apparatuses, there is an image forming apparatus of four-drum multi transfer type (referred to as xe2x80x9cin-line color printerxe2x80x9d hereinafter) in which a plurality of photosensitive drums as a plurality of electrophotographic photosensitive members are disposed side by side along a conveying direction of a transfer material, developing means such as developing devices containing different color toner are opposed to the respective photosensitive drums, and a full-color image constituted by four color toners is formed on the transfer material conveyed by means of a transfer belt and the like by successively transferring different color toner images formed on the photosensitive drums and developed by the developing means onto the transfer material.
This system can obtain a print image at a higher speed in comparison with an image forming apparatus of type in which different color toner images are successively transferred onto an intermediate transfer member in a superimposed fashion by using a single photosensitive drum and then the toner images are collectively transferred onto a transfer material.
FIG. 6 shows an example of such an in-line color printer. In FIG. 6, an endless transfer belt 6 is mounted on drive rollers 7 and is rotated in a direction shown by the arrow. Along a transfer material conveying direction of the transfer belt 6, there are provided image forming portions Y, M, C and Bk for yellow Y, magenta M, cyan C and Black Bk disposed side by side.
The image forming portions Y, M, C and Bk have similar constructions and include photosensitive drums 1a, 1b, 1c, 1d arranged in series along the transfer material conveying direction of the transfer belt 6, charging rollers 2a, 2b, 2c, 2d as contact type charging means, developing means 4a, 4b, 4c, 4d and cleaning means 5a, 5b, 5c, 5d, which means are located around the respective photosensitive drums.
Now, an image forming operation will be described. Laser beams 3a, 3b, 3c, 3d modulated in accordance with image data from a host computer such as a personal computer are illuminated onto surfaces of the photosensitive drums 1a, 1b, 1c, 1d uniformly charged by the charging rollers 2a, 2b, 2c, 2d, thereby obtaining desired electrostatic latent images. These latent images are visualized as toner images by reversal developing at respective developing areas effected by the developing means 4a, 4b, 4c, 4d as the developing devices containing the different color toners. The toner images are electrostatically transferred onto a transfer material P fed by sheet feeding means (not shown) and conveyed by the transfer belt 6 under the action of transfer means 8a, 8b, 8c, 8d at respective transfer nip portions. Further, after the transferring, non-transferred residual toners remaining on the photosensitive drums 1a, 1b, 1c, 1d are removed by the cleaning means 5a, 5b, 5c, 5d such as cleaning blade, respectively, for preparation for next image formation.
In the image forming apparatus according to this example, the photosensitive drums 1a, 1b, 1c, 1d, charging rollers 2a, 2b, 2c, 2d, developing means 4a, 4b, 4c, 4d and cleaning means 5a, 5b, 5c, 5d are integrally incorporated in cartridge units, respectively, to obtain process cartridges (CRG) 9a, 9b, 9c, 9d as shown in FIG. 7. Incidentally, FIG. 7 shows a process cartridge 9a for yellow color including toner supplying means 20a for supplying toner into the developing means or developing device 4a. The toner supplying means 20a comprise a toner container 21a containing toner to be supplied, and a toner supplying mechanism 22a for feeding the toner to the developing device 4a. 
In FIG. 7, the toner container 21a containing the yellow toner is connected to the developing device 4a through the toner supplying mechanism 22a so that, when the fact that an amount of toner in the developing device 4a is decreased below a predetermined amount is detected by appropriate detecting means, a predetermined amount of the yellow toner in the toner container 21a is supplied into the developing device 4a by the toner supplying mechanism 22a. Regarding the other colors, the similar arrangements are adopted. Namely, for magenta color toner, cyan color toner and black color toner, there are provided process cartridges 9b, 9c, 9d and toner supplying means 20b, 20c, 20d containing respective toners.
Although various developing systems have been proposed in the past, in the apparatus shown in FIG. 6, any developing system of contact type or non-contact type may be used and one-component toner or two-component toner may be used as toner or developer. As an example, there is a jumping developing method of non-contact type using non-magnetic one-component toner.
The process cartridges 9a, 9b, 9c and 9d can be detachably mounted on a main body of the image forming apparatus. Further, the image forming apparatus has means for detecting service lives of the respective cartridges so that, even if the service life of any cartridge is expired, the image forming apparatus can be used continuously by exchanging such a cartridge with a new one by the operator.
In the recent laser printers, in many cases, a process cartridge which does not require maintenance which is exchange of worn part such as photosensitive member or developer difficult to be replaced by the user, waste toner treatment and the like, and which is detachably attachable to the image forming apparatus has been used. For example, various process cartridges such as a developing cartridge obtained by integrally incorporating a container containing toner and developing means, a drum cartridge obtained by integrally incorporating a photosensitive member, charging means and cleaning means and a cartridge obtained by integrally incorporating such a developing cartridge and such a drum cartridge have been proposed.
In these process cartridges, a service life is alarmed in accordance with a worn extent of each part, and each process cartridge can be exchanged by the user himself. Further, since each cartridge is designed to optimize its service life, a good image having no inconvenience can always be obtained until the service life of the cartridge is expired, and the operator can easily exchange the expired cartridge to a new one.
However, in the image forming apparatus as shown in FIG. 6, when the user firstly mounts the process cartridge to the image forming apparatus after he bought it, it is required that four process cartridges for respective colors Y, M, C, Bk be mounted to predetermined positions. Further, when the service life of any process cartridge is approached, if a corresponding new process cartridge is not prepared, upon expiration of the process cartridge, the image forming apparatus cannot be further used.
As mentioned above, although the advantage that any expert is not required by using the cartridge in the electrophotographic apparatus can be obtained, in the color image forming apparatus, at least four additional process cartridges for respective colors must be previously prepared. Normally, the service lives of the four color process cartridges are rarely expired simultaneously, and, thus, continual preparation of four kinds of process cartridges burdens the user with high expense. Particularly, for the user who operates and controls a plurality of apparatuses, since the storing condition of the respective color cartridges must be ascertained in accordance with the operating condition, inconvenience is increased.
On the other hand, makers for manufacturing the process cartridges perform manufacturing control such as sorting the cartridges for respective colors and production adjustment, and, thus, the makers are burdened with great load in the process cartridges for the color image forming apparatus. In general, the developing devices for respective colors are designed to have no difference in construction in order to reduce the cost by using the identical parts.
However, even when designed in this way, nowadays, in order to prevent user from erroneous mounting, specifications of process cartridges are made to be different from each other. For example, configurations of the cartridge containers for respective colors have been partly changed, seals identifying particular colors have been adhered to the cartridges for respective colors or colors of packages for the respective color cartridges have been changed. Thus, the number of parts are increased to increase the cost in comparison with the case where the identical process cartridges are manufactured.
The present invention aims to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide an image forming apparatus which can reduce the burden of the users and/or makers, and a cartridge detachably attachable to such an image forming apparatus.
Another object of the present invention is to provide an image forming apparatus having low cost, and a cartridge detachably attachable to such an image forming apparatus.
A further object of the present invention is to provide an image forming apparatus comprising a plurality of cartridges each having a toner container and a memory and detachably attachable to a main body of the image forming apparatus, a plurality of supplying means for supplying toners to the respective toner containers, and a plurality of writing means for writing information in the respective memories, and wherein, when a new cartridge is mounted, the writing means write color information corresponding to a mounting position in the memory.
The other object of the present invention is to provide a cartridge comprising a toner container and a memory, and wherein, in a condition that the cartridge is never mounted to an apparatus, the toner container is empty.
The other objects and features of the present invention will be apparent from the following detailed explanation of the invention referring to the accompanying drawings.